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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 109, D05101, doi:10.1029/2003JD004245, 2004

Interdecadal changes in seasonal freeze and thaw depths in Russia

Oliver W. Frauenfeld

Division of Cryospheric and Polar Processes, Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA


Tingjun Zhang

Division of Cryospheric and Polar Processes, Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA


Roger G. Barry

Division of Cryospheric and Polar Processes, Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA


David Gilichinsky

Soil Cryology Laboratory, Institute of Physico-Chemical and Biological Problems in Soil Sciences, Russian Academy of Sciences, Pushchino, Moscow Region, Russia


Abstract

Seasonal freezing and thawing processes in cold regions play a major role in ecosystem diversity, productivity, and the Arctic hydrological system. Long-term changes in seasonal freeze and thaw depths are also important indicators of climate change. Only sparse historical measurements of seasonal freeze and thaw depths are available for permafrost and seasonally frozen ground regions. Using mean monthly soil temperature data for 1930–1990 for 242 stations located throughout Russia, we employed a linear interpolation method to determine the depth of the 0°C isotherm based on soil temperature data measured between 0.2 m and 3.2 m depth. The relationship between available observed annual maximum freeze and thaw depths and our interpolated values indicates a perfect correlation. A comprehensive evaluation of long-term trends in these new interpolated data for Russia indicates that in permafrost regions, active layer depths have been steadily increasing. In the period 1956–1990 the active layer exhibited a statistically significant deepening by approximately 20 cm. The changes in the seasonally frozen ground areas are even greater: The depth of the freezing layer decreased 34 cm between 1956 and 1990. Potential forcings of the observed changes include air temperature, freezing and thawing index, and snow depth. Correlation and multiple regression reveal that active layer depth is most strongly related to snow depth. Air temperature, both mean annual and thawing index, is also significantly related to changes in the active layer. Freeze depth is influenced most strongly by the freezing index and mean annual air temperature, although snow depth is also a significant contributor. Air temperature and snow depth have been changing less in the seasonally frozen ground regions of Russia compared to permafrost regions, although observed changes in freeze depth are greater than changes in active layer depth for 1930–1990. This indicates that the seasonally frozen ground regions of the Russian high latitudes are more susceptible to climate change than the Russian permafrost. However, as temperatures have been rising, especially in the high-latitude continental regions, both permafrost and seasonally frozen ground regions are being greatly impacted. These changes can potentially result in increased river runoff and changes in discharge throughout the Russian Arctic drainage basin, as well as changes in high-latitude ecosystems.

Received 13 October 2003; accepted 14 January 2004; published 3 March 2004.

Index Terms: 1699 Global Change: General or miscellaneous; 1823 Hydrology: Frozen ground; 1863 Hydrology: Snow and ice (1827); 3309 Meteorology and Atmospheric Dynamics: Climatology (1620); 3322 Meteorology and Atmospheric Dynamics: Land/atmosphere interactions.

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Citation: Frauenfeld, O. W., T. Zhang, R. G. Barry, and D. Gilichinsky (2004), Interdecadal changes in seasonal freeze and thaw depths in Russia, J. Geophys. Res., 109, D05101, doi:10.1029/2003JD004245.